Biomimetic Functionalization of Gold Nanoparticles and Nanopyramids with Keratin

Gold nanoparticles (AuNPs) attracted considerable research efforts in the last few decades. Their synthesis and functionalization were studied for optical as well as for biomedical applications. AuNPs have excellent biocompatibility, tunable optical properties and stimuli-responsive properties. In this regard, the light-to-heat conversion efficiency of AuNPs do to their plasmonic resonance was key for the development of a drug-free cancer therapy method named plasmonic photo-thermal therapy (PPT).<br/>In particular, gold particles in the shape of bypyramids have their plasmonic absorption in the 800 - 900 nm range, within the relative transparency window of biological tissues, and possess greater light to heat conversion, making them even more interesting for PTT.<br/>The scope of this work is to explore how keratin proteins conjugated on AuNPs of different shape can provide an efficient functionalization that is able to promote their utilization for the realization of a drug-free cancer therapy. Our results highlight that this new generation of Ker-AuNPs exhibits outstanding biocompatibility and stability in the biological environment. They showed elevate tumor accumulation due to their capability to bind/penetrate in cancer cells and excellent photo-thermal properties.<br/>Furthermore the keratin layer on the gold particles provided a platform for further functionalization of the gold particles, from fluorescent labeling, to radiolabeling with Tc, enabling their use for different imaging techniques.<br/>In vitro experiments, performed on a human glioblastoma cell line (i.e. U87-MG), by means of viability assays, TEM, fluorescence microscopy, and cytometric analyses combined with PPT experiments confirm the excellent biocompatibility as well as their efficient cellular uptake and localized photo-thermal heating capabilities.